1. Technical Field
The present invention is related to a method and system to be utilized in a multiple protocol environment. In particular, the present invention is related to a method and system to be utilized in a multiple protocol environment wherein the method and system allow one or more protocols overlaid onto one or more base protocols to utilize the one or more base protocol information in order to provide efficient communications between entities utilizing said overlaid protocols. Yet still more particularly, the present invention is related to a method and system to be utilized in a multiple protocol environment where one of the protocols can be Asynchronous Transfer Mode and wherein the method and system allow protocols overlaid onto an ATM protocol to utilize ATM protocol information in order to provide efficient communications between entities utilizing said overlaid protocols.
2. Description of the Related Art
The present invention is directed toward remedying deficiencies and solving problems relating to the overlaying of one or more base protocols with one or more other protocols intended to extend the capabilities and functionalities of the one or more underlying base protocols. For sake of illustration, the discussion of the present invention is directed toward remedying deficiencies and solving problems relating to the overlaying of Asynchronous Transfer Mode (ATM) protocols with protocols intended to extend the capabilities and functionalities of the underlying ATM protocols. However, those skilled in the art will recognize that the discussion is not limited to ATM but extends to the general deficiencies and problems that relate to the overlaying of one or more base protocols with one or more other protocols intended to add capabilities and functionalities to the one or more underlying base protocols.
ATM is a communications protocol that (a) enables the transmission of voice, data, image, and video signals over wide area, high bandwidth communications systems; (b) provides fast packet switching in which information is inserted into small fixed size cells that are multiplexed and switched in a slotted operation, based upon header content, over a virtual circuit established immediately upon request for service; (c) has been chosen as the switching standard for broadband integrated services digital networks (BISDNs); (d) has variable transmission rates; (e) offers bandwidth on demand service, and (f) supports multiple concurrent connections over single communications lines. Weik, Communications Standard Dictionary 47 (3rd ed. 1996).
As stated, ATM is a type of fast packet switching protocol. A packet, in data communications, is a sequence of binary digits that has one or more of the following characteristics: (a) includes data, control signals, and possibly error control signals, (b) is transmitted and switched as a composite whole, (c) is arranged in a specific format, such as a header part and a data part, (d) may consist of several messages or may be part of a single message, (e) is used in asynchronous switched systems, and (f) is usually dedicated to one user for a session. Weik, Communications Standard Dictionary 690 (3rd ed. 1996). A fast packet switching protocol increases the speed of packet switching by eliminating overhead (i.e., information in a packet which is solely utilized for efficient and correct communications and has no information content of interest to the ultimate network user). Weik, Communications Standard Dictionary 690 (3rd ed. 1996).
In an ATM protocol network fast packet switching protocol overhead is reduced by (1) allocating flow control (making sure that a network node's buffer capacity is not exceeded) and error control (making sure that information is not corrupted) to nodes within the network, and (2) providing different Quality of Service (with lower Quality of Services requiring less overhead) dependent upon requirements received from ATM protocol network users.
The ability of ATM to provide different Quality of Service is one of the greatest advantages of ATM. These different qualities of service allow data communications networks to carry, in an integrated way, both real-time traffic such as voice and high resolution video which can tolerate some loss but not delay, as well as non-real-time traffic such as computer data and file transfer which may tolerate some delay but not loss. The problem with carrying these different types of traffic on the same medium in an integrated fashion is that the peak bandwidth requirement of these traffic sources may be quite high as in high resolution full motion video, but the duration for which the data is actually transmitted may be quite small. In other words, the data comes in bursts and must be transmitted at the peak rate of the burst, but the average arrival time between bursts may be quite large and randomly distributed.
In the judgement of telecommunication industry analysts, the indicated trend for multimedia integrated telecommunications and data communications demands of global economies in the late 90's and early 21st century is for the foregoing discussed types of data traffic to increase. ATM provides the mechanisms whereby such user data demands may be satisfied without unduly consuming network communications resources. Hence, there is tremendous pressure from the telecommunications industry to move toward ATM protocol networks.
Unfortunately for the telecommunications industry, there exists today a tremendous installed base of non-ATM protocol networks (e.g., Wide Area Networks (WANs), Local Area Networks (LANs), Internet Protocol Networks) which do not utilize ATM protocol. Furthermore, some of the non-ATM protocol networks have features, which ATM protocol networks do not provide but that user systems have come to rely upon and have been designed to utilize. Thus, the telecommunications industry has been in a quandary in that the industry desires to move to ATM protocol networks, but a huge percentage of its customer base has previously invested in hardware and software designed for non-ATM protocol networks.
The telecommunications industry has opted for an attrition strategy to solve this problem. Under this strategy, the industry has opted to move toward ATM protocol networks while simultaneously continuing to support the vast installed base of non-ATM protocol networks, and the network and link layer protocols operating on these networks. (The hope being that as new users come on line they will utilize ATM protocol equipment and that as older systems are phased out, they will be replaced with ATM protocol systems.) The key to this strategy is empowering the ATM protocol networks to be able to support non-ATM protocols, and to be able to supply non-ATM features which users have come to expect and rely upon.
The telecommunications industry has opted to provide such support and supply such features via various "overlay" schemes. While the specifics of any particular overlay implementation are horrendously complex, the general idea is relatively straightforward: any non-ATM capability will be provided by a (logically) separate protocol that is (logically) overlaid onto a base ATM protocol network. The (logically) overlaid protocol is then utilized to allow non-ATM protocol networks to interact with ATM protocol networks "as if" the ATM protocol networks were a part of, and hence recognize the protocols and support the features of, non-ATM protocol networks. Three of the more well-known overlay schemes are the following: Local Area Network Emulation (which allows a local area network station on one local area network to communicate with other one or more stations not on the local area network by and through an ATM protocol network "as if" the stations were in fact on the local area network); Multicast Operation (a scheme which allows an ATM protocol network to support and appropriately respond to a request from an Internet Protocol network for a multicast operation); and Resource Reservation Protocol (RSVP) (a very high level scheme which allows internetworked disparate base subnetworks to guarantee a Specified Quality of Service on a communications link irrespective of the functioning of the underlying base subnetworks). These schemes will be discussed under the detailed description of illustrative embodiments section, below.
While the foregoing noted schemes of overlaying work well from the standpoint of allowing non-ATM protocol networks to communicate with and through ATM protocol networks, there are deficiencies in such an approach.
One deficiency is that such overlaying schemes do not make use of the capabilities of a tremendous amount of information inherent within an ATM protocol network.
It was stated above that ATM protocol networks support the ability to efficiently transport many types of data by providing many different Qualities of Service. While the specifics of how this is done need not be discussed at this point, a way in which this is achieved is to make the ATM protocol network nodes more autonomous (i.e., allowing the nodes to make data handling decisions in a more independent fashion than generally allowed in non-ATM protocol networks). The ATM protocol network nodes are able to achieve this autonomy because such nodes have access to a tremendous amount of information about the data handling capabilities of other ATM protocol network nodes in the ATM protocol network. This information is intermittently disseminated throughout the ATM network by each ATM protocol network node "flooding" (i.e., simultaneously transmitting to many nodes within the ATM protocol network) the network with its (the flooding node's) current data handling capacity. The ATM protocol network nodes then utilize this information about other nodes to autonomously make routing decisions.
The foregoing described network overlay schemes are not actually part of the ATM protocol, but rather are ways of overlaying a non-ATM protocol onto an ATM protocol. Because these overlaying schemes are not actually part of the ATM protocol, the participants in the schemes are generally not privy to all the inter-nodal communication which is being utilized by the ATM protocol network to provide Quality of Service guarantees. That is, generally the overlaying schemes are somewhat "dumb" in that they are not part of, and do not take advantage of, information related to the data handling capacities of the different nodes in the underlying ATM protocol networks. Because the participants in the overlay schemes are not privy to such internodal communication, such participants will often request Quality of Service communication links to other overlay scheme participants which exceeds the quality of service capabilities of the ATM protocol network nodes that are to support such communications links between overlay participants.
Once an overlay scheme participant (hereinafter the "source participant") requesting a communications link to another overlay scheme participant (hereinafter the "destination participant") finds out that the ATM protocol network cannot support the requested Quality of Service, the source participant can enter into negotiation, via the ATM network, with the destination participant with which the source participant wishes to establish contact. This negotiation is engaged in to determine what Quality of Service the ATM network can support between the two participants. Alternatively, the source participant will engage in a best-effort operation. In either case, the source participant continues to request a progressively lower quality of service link with the destination participant until either the destination can accommodate the source (i.e., a connection is established) or the attempt to establish communications fails. Both scenarios (negotiation and best effort) generally require much time and consume much network bandwidth.
The scenarios are so time and bandwidth intensive because source participants are generally unaware of the underlying ATM protocol network capabilities. Consequently, should an initial request for a communications link fail, the source participant essentially just keeps retrying to establish a link with the destination participant at successively lower qualities of service until a link is successfully established. Such negotiation would not have been necessary had the source participant been privy to the network traffic information which was resident within the ATM protocol network, since the source participant would have known at the outset the communications capabilities that the ATM protocol network could support between the source participant and the destination participant with which the communications link is to be established.
Thus, it is apparent from the foregoing that a need exists for a method and system which allows participants utilizing protocols, overlaid onto ATM protocol networks for the purpose of extending the capabilities of ATM protocol networks, to utilize ATM protocol network information in order to provide more efficient communications between entities utilizing the overlaid protocols.